Examples for 8th grade - page 3

  1. Reverse Pythagorean theorem
    pytagors Given are lengths of the sides of the triangles. Decide which one is rectangular: Δ ABC: 73 m, 66 m, 51 m ? Δ DEF: 63 cm, 105 cm, 84 cm ? Δ GHI: 50 dm, 48 dm, 14 dm ? Δ JKL: 31 m, 45 m, 40 m ? Δ MNO: 28 m, 53 m, 45 m ?
  2. Proof PT
    pytagoras Can you easy prove Pythagoras theorem using Euclidean theorems? If so, do it.
  3. Root
    root_quadrat The root of the equation ? is: ?
  4. Troops
    regiment Route is long 203 km and the first day first regiment went at an average speed 20 km/h and journey back 19 km/h. The second day went second regiment same route at an average speed 18 km/h there and back. Which regiment will take route longer?
  5. Flags
    vlajka_cz How many different flags can be made from colors red, white, blue, black, yellow, green, purple, gray, orange so that each flag consisted of three different colors?
  6. Triangle
    eq_triangle Can be rectangular triangle equilateral?
  7. Above 100%
    dummy What is 155% of 210?
  8. Guests
    hostia How many ways can 7 guests sit down on 9 seats standing in a row?
  9. Stock market
    money_1 Simon one day decided to invest € 88000 to the stock market. After six months he invested July 5 stock markets fell by 56%. Fortunately for Simon from July 5 5 to October 5 his shares have risen by 39%. Simon is then: ?
  10. Height
    thales_law Is right that in any right triangle height is less or equal half of the hypotenuse?
  11. Logs
    gulatina Trunk diameter is 72 cm. Is it possible to inscribe a square prism with side 54 cm?
  12. Playing cards
    playing_cards How many possible ways are to shuffle 7 playing cards?
  13. Series
    posloupnost_an Andrew wrote this series of numbers: 1,3,7,15, .... n. Which number in the series does not belong? ?
  14. Shelf
    bookshelf.JPG How many ways are there to arrange 9 books on a shelf?
  15. Ace
    ace From complete sets of playing cards (32 cards) we pulled out one card. What is the probability of pulling the ace?
  16. Logic
    blue-barrel A man drinks a barrel of water for 31 days, woman for 58 days, for how many days they drink barrel together?
  17. Percent calculation
    percent_sign Calculate 72% if 96% is 93.
  18. Trapezoid
    rectangular_trapezoid Are diagonals in a rectangular trapezoid perpendicular and bisect the angles?
  19. Road
    cesta Between cities A and B is route 3 km long of rise average 4‰. Calculate the height difference of cities A and B.
  20. Painter Pavel
    pixla_s_farbou Painter Pavel painted the fence for 20 hours and painter Petr the same fence painted for 17 h. How long should take painted the fence together?

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